The U.S. Navy is committed to maintaining and improving its systems and techniques used to rescue survivors from a disabled submarine. Rescue operations can be required in a variety of situations to include those where the disabled submarine becomes internally pressurized due to flooding, leakage of compressed gas supplies, or through use of auxiliary breathing systems.
Efficient submarine rescue requires that pressurized crew members be decompressed more rapidly than current decompression procedures allow when using air. It has been shown that crew decompression can be accelerated significantly by having crew members pre-breath oxygen using, for example, face masks supplied with either pure oxygen or an oxygen-rich breathing gas. Unfortunately, such oxygen pre-breathing can result in oxygen buildup in the cabin atmospheres of the submarine through leakage around the face seal of the oxygen masks or leakage from the oxygen supply. High levels of oxygen can create hazardous conditions within the cabin atmosphere due to increased fire potential and/or oxygen toxicity.